Analysis of Thumb and Index Finger Joints During Pinching Motion and Writing a Cross, as Measured by Electrogoniometers

Abstract

The purpose of this study is to determine the flexion angle of the thumb and the index finger joints while using a pinching motion to write a cross, observed with flexible goniometers. (1) The pinching motion: the flexion angles of the joints of the thumb and the index finger under 100-g and 1000-g pressure pinch were measured at 0, 1, 2, 3, and 5 cm distances of pulp pinch and tip pinch. The flexion angle of the index metacarpophalangeal (MP) joint was decreased as the distance of the pinch was increased, but the flexion angles of other joints were almost the same in any distance of the pinch. (2) Writing a cross: the size of the cross was set at either 4 or 6cm. One cycle was started by writing a horizontal line from left to right and then a vertical line from up to down, returning to the starting point. The most mobile joint was the interphalangeal (IP) joint of the thumb, followed by the proximal interphalangeal (PIP) joint of the index finger. The less mobile were the MP joints of the both digits. This flexible goniometer will be useful in the motion analysis of the finger joints of both normal and diseased hands.